New BitcoinV Release v0.18.1

https://github.com/bitcoinVBR/bitcoinV/releases/tag/v0.18.1

Merged BitcoinV VBR feature into Bitcoin v0.18.1:
https://github.com/bitcoin/bitcoin/releases/tag/v0.18.1

Use bitcoin.conf setvbrmultiplier option to set VBR amount.